1 Field of the Invention
The invention described herein relates to a method of mining which employs leach solutions to recover materials by using a single injection/recovery well.
2 Description of the Prior Art
The current basic practice in situ leach mining field which utilizes injection solutions requires the drilling of a separate hole for each of several wells. Most of these wells are usually injection wells and one or more are recovery wells. Normally these holes are drilled to depths greater than 300 feet and then each cemented and cased to the surface. For the typical inverted 5-spot or 7-spot pattern used in situ leach mining, one recovery well is surrounded by four or six, as the case may be, injection wells. Other patterns of injection/recovery wells are possible such as those described in the commonly assigned copending U.S. patent application bearing Ser. No. 60101 filed July 24, 1979, and entitled "Method of In Situ Mining," or those described in Bureau of Mines Information Circular (IC)-8777, titled "Uranium in Situ Leach Mining in the United States."
With these prior art practices there is considerable time and expense involved in the drilling, moving, and setting up of the drill rig and other associated equipment for drilling each well hole. In addition, when deep holes (more than 1,000 feet) are drilled vertical deviations become a serious problem particularly where the injection and recovery wells are less than 50 feet apart. Not only are the above problems greatly reduced or practically eliminated by using a single injection/recovery well, as we propose herein, the total footage of drilled material would be considerably less than the present state of the art 5 spot pattern since all of the separate injection wells are eliminated.
None of the known patent or other prior art is concerned with multiple completions for in situ leach mining. U.S. Pat. No. 2,171,416 (R. E. Lee) is concerned with a method of drilling wells by using angular (approximately 90 degrees) drilling at the bottom of the hole to enlarge the productive area of the well. Within these branch channels acid, other chemicals or explosive charges are used to stimulate oil and gas production by introducing them thereto. A pump may be used (column 2, lines 30-38) to introduce the acid or other chemical into the central tube placed in the main vertical drill hole. Nothing is said about using leaching solutions in an injection/recovery type of well to obtain underground minerals from an ore zone.
Other United States patents of interest include U.S. Pat. Nos. 3,223,158 (Baker), 3,941,422 (Henderson), 3,978,926 (Allen), and 4,022,279 (Driver). None are believed any more relevant than the mentioned R. E. Lee patent nor do they relate to mining using leaching solutions that employ a single injection/recovery well.